a modeling tool that fully exploits product...

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A modeling tool that fully exploits product modularization

Henrik Wentzel

Truck Chassis Development - Simulation

Scania CV AB


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My niece loves Lego…


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...my president of R&D loves engines


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If all goes well my niece will take over his job in 40 or so years.

how will that change Scania?


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It will not change the modular system

LegoScanias modular

system


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Modularization allows for many vehicles but few parts

90 % same

components


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It is challenging to validate modules

Turbo installation

Should it be tested

here?

…or here?


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Simulation is a cheap and fast way to address quality


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A key challenge is then to generate and maintain many FE-models


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The true engineer does not want to,

� mesh every M10 bolt in the truck.

� remesh the turbo installation for 10 different configurations.

� remesh the exhaust installation when the colleague already has it meshed.


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Alternatives that may make meshing less laborious include

� Batch-meshing

� Low wage engineers

� Model library


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We have gone for the model library!

� Each part has a part no.

� Each part has a drawing.

� A Catia session may easily be assembled for any complete vehicle, providing all part nos. and positioning.


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Mesh libraryGeometry library

The model building process

Vehicle

specificationSession - file

Finite element

model

Pre-processing

environment

Spectra Catia v5 Hypermesh Abaqus


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Important steps in the model building process

•Reading CAD libraries and automatically selecting

appropriate files

•Positioning components to their correct location in the

chassis

•Mesh generation on geometries that are not found in the

mesh-library

•Cutting holes in geometries/meshes to prepare for bolt

connections

•Generating “spider connections,” solid bolts with pre-tension

and contact definitions


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Example – meshing a truck


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Chassis no. gives a geometry session


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We strip down to chassis components


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We now have a file of ingoing parts and their positioning – (session file)

/home/sssnto/fem/ram/avgas/vanster/mod FEM-1740196-1-1-7-GEO-

BRACKET-SSSUKI 1.000000 0.000000 0.000000 0.000000 1.000000

0.000000 0.000000 0.000000 1.000000 0.000000 0.000000 0.000000


PILLAR-VERTICAL-ASSY-SSSMGP 1.000000 0.000000 0.000000

0.000000 1.000000 0.000000 0.000000 0.000000 1.000000 3026.000000

-1218.500000 14.999800


BRACKET-SSSMGP 1.000000 0.000000 0.000000 0.000000 1.000000

0.000000 0.000000 0.000000 1.000000 3040.000000 -1018.500100

14.999800

/dfs/site/sss/store/fem/components_abq/001 FEM_1431599-1-1-15-21-01-

SSSARA 1.000000 0.000000 0.000000 0.000000 1.000000 0.000000

0.000000 0.000000 1.000000 0.000000 0.000000 0.000000

……………………..


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This session file is opened in hypermesh


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For every part we choose to import either Catia geometry, FE-mesh or HM model


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The result is a mesh


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If a part is not found in the mesh-library, the geometry is imported instead.


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When all parts are meshed we have a model


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but the parts are not connected!


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We start by filling in the over-sized bolt holes


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then bolts are added, here as orange “spiders”


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Each bolt now has a text-tag (green, yellow or magenta)


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Active connections are green


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“Loose” bolts are yellow or magenta


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When components are attached we export the FE-mesh for simulation


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Tricky things model building process

•If several meshes exist, how to select the most appropriate

one. (Different mesh refinement, latest geometry version,

etc.)

•How is a bolted connection modelled? (standardization of

model and interface)

•How does the engineer make sure that all the connections

are “connected” (All the nuts tightened). This is a real

problem on the production line.

•When a part is updated, how is notification given to all

analyses that make use of that part?


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Key benefits – quality and time

� Quality, because the process is repeatable and not so dependent on the engineer. The latest up-to date mesh is always used.

� Time, because the assembly of a full vehicle, including bolted connections, takes only a couple of hours with the session browser.

a modeling tool that fully exploits product...

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